horticulturist
person who works and conducts research in the science and art of growing flowers, fruits, vegetables or ornamental plants
rose breeder
person who is specialized in breeding roses
plantsman
enthusiastic and knowledgeable gardener (amateur or professional), nurseryman or nurserywoman. "Plantsman" can refer to a male or female person, though the terms plantswoman, or even plantsperson, are sometimes used
plant breeder
occupation; person engaged in the breeding of plants
pomologist
person studying pomology